1. Field of the Invention
The present invention relates to an image processing device, a computer readable storage medium storing an image processing program, and an image processing method that are used in processing a series of intra-gastrointestinal-tract images captured by an image pickup device while moving inside a gastrointestinal tract.
2. Description of the Related Art
An image pickup device such as a capsule endoscope that can capture a series of intra-gastrointestinal-tract images while moving inside a gastrointestinal tract has been developed in recent years. Upon being swallowed from mouth and while being carried through the gastrointestinal tract due to the peristaltic motion, a capsule endoscope sequentially captures images at a predetermined image capturing rate and transmits the images to an external receiving apparatus. Eventually, the capsule endoscope is passed out of the body. Broadly, the number of captured intra-gastrointestinal-tract images is indicated by an image capturing rate of “(about 2 to 4 frames/sec)×length of stay in body (about 8 hours=8×60×60 sec)”, which comes to several tens of thousands of images. Thus, to confirm that large number of images on a diagnostic workstation or the like, a doctor needs to spend a considerable amount of time. For this reason, there is a strong demand for a technology that would streamline the image confirmation task performed by a doctor.
For example, Japanese Patent Application Laid-open No. 2006-122502 discloses a technology that distinguishes, from among a large number of intra-gastrointestinal-tract images captured by a capsule endoscope, images including a mucosal area or a gastrointestinal contents area of gastrointestinal contents such as feces so that unwanted images such as images including almost no mucous membrane can be deselected. More particularly, each pixel in an image is mapped to a feature space (arctan (g/r), arctan (b/r), etc.) that is based on the color information of that pixel. Then, by performing comparison with a distribution range within a feature space of the previously obtained pixels belonging to the mucosal area or the gastrointestinal contents area (teaching data), it is determined to which area range each pixel in the image belongs and then the mucosal area or the like is identified.